The present invention relates to electro-active lenses, which may include, for example, ophthalmic lenses such as spectacle lenses, and/or non-ophthalmic lenses, such as a camera lens, etc. More specifically, the present invention relates electro-active cells including one or more thin glass layers, as well as to lenses which may include such cells.
Electronic lenses and electronic focusing eyeglasses are known and now commercially available. U.S. Pat. Nos. 6,619,799; 7,290,875; 6,626,532; and 7,009,757 (the contents of which are hereby incorporated by reference herein for all purposes) are presented as selective examples of electronic focusing ophthalmic lenses and/or eyeglasses that teach how an electronic lens or electronic focusing eyeglasses are made.
Presently the only electronic focusing eyeglasses commercially available are retailing for about $1,250 for a pair which includes the electronic frames, electronic lenses, charger, and all coatings. There are two major components that drives up the cost of goods of such electronic focusing eyeglasses and both pertain to the cost of the electronic lenses. Presently the electronic lenses have to be made out of an expensive 1.67 optical grade plastic called MR 10 sold by Mitsui. This is because the index of refraction of the diffractive region and the liquid crystal must be closely matched when the electronic lens is turned off. In addition to a good index match in the off state, it is important to maintain a relatively small diffractive height (less than 4 microns ideally). This requires a relatively large average index of the LC needs, so that the change in index when the lens is activate is large enough to produce the desired amount of phase shift for a relatively thin layer of liquid crystal.
Because the diffractive region is located on the external front surface of the 1.67 back semifinished lens blank, the significant bulk of the material with the present electronic focusing lens is made from an expensive premium material. And because the index of the liquid crystal must closely match that of the 1.67 back, the material selection which can be used to make today's commercially available electronic focusing ophthalmic lens is very much limited.
Thus there is a pressing need for an ophthalmic focusing lens and/or electronic eyeglasses that allows for a much lower cost of goods and is material independent. By material independent it is meant allows for a plurality of different materials which comprises the bulk the electronic semi-finished lens blank.
Other factors to consider include the fact that, while plastic lenses are light weight, they have tendency to scratch. On the other hand, glass is highly scratch resistant but is heavy. Glass-plastic composite lenses have been tried in the past but have tended to fail due to thermal expansion differences causing delamination of the glass from the plastic.
Also, with electronic eyeglasses, the front lid is approximately 1.3 mm thick. For grooved lenses the groove is set at 1.3 mm from front thus the groove is located at the interface of the front lid optical substrate and the back optical substrate.
With regard to electronic spectacle lenses there is a need for improved and novel ways to create less expensive lens products that meet safety and durability standards.